Conventional optical trapping or tweezing is often limited in the achievable trapping range because of high numerical
aperture and imaging requirements. To circumvent this, we are developing a next generation BioPhotonics Workstation
platform that supports extension modules through a long working distance geometry. This geometry provides three
dimensional and real time manipulation of a plurality of traps facilitating precise control and a rapid response in all sorts
of optical manipulation undertakings. We present ongoing research and development activities for constructing a
compact next generation BioPhotonics Workstation to be applied in three-dimensional studies on regulated microbial cell
growth including their underlying physiological mechanisms, in vivo characterization of cell constituents and
manufacturing of nanostructures and new materials.
Optical trapping and manipulation have established a track record for cell handling in small volumes. However, this cell
handling capability is often not simultaneously utilized in experiments using other methods for measuring single cell
properties such as fluorescent labeling. Such methods often limit the trapping range because of high numerical aperture
and imaging requirements. To circumvent these issues, we are developing a BioPhotonics Workstation platform that
supports extension modules through a long working distance geometry. Furthermore, a long range axial manipulation
range is achieved by the use of counter-propagating beam traps coupled with the long working distance. This geometry
provides three dimensional and real time manipulation of a plurality of traps - currently 100 independently
reconfigurable - facilitating precise control and a rapid response in all sorts of optical manipulation undertakings. We
present ongoing research activities for constructing a compact next generation BioPhotonics Workstation.
In its standard version, our BioPhotonics Workstation (BWS) can generate multiple controllable counter-propagating
beams to create real-time user-programmable optical traps for stable three-dimensional control and manipulation of a
plurality of particles. The combination of the platform with microstructures fabricated by two-photon polymerization
(2PP) can lead to completely new methods to communicate with micro- and nano-sized objects in 3D and potentially
open enormous possibilities in nano-biophotonics applications. In this work, we demonstrate that the structures can be
used as microsensors on the BWS platform by functionalizing them with silica-based sol-gel materials inside which dyes
can be entrapped.
We present a versatile technique that enhances the axial stability and range in counter-propagating (CP) beam-geometry optical traps. It is based on computer vision to track objects in unison with software implementation of feedback to stabilize particles. In this
paper, we experimentally demonstrate the application of this technique by real-time rapid repositioning coupled with a strongly enhanced axial trapping for a plurality of particles of varying sizes. Also exhibited is an interesting feature of this approach in its ability to automatically adapt and trap objects of varying dimensions which simulates biosamples. By working on differences rather than absolute values, this feedback based technique makes CPtrapping nullify many of the commonly encountered pertubations such as fluctuations in the laser power, vibrations due to mechanical instabilities and other distortions emphasizing its experimental versatility.
The counter-propagating geometry opens an extra degree of freedom for shaping light while subsuming single-sided
illumination as a special case (i.e., one beam set turned off). In its conventional operation, our BioPhotonics Workstation
(BWS) uses symmetric, co-axial counter-propagating beams for stable three-dimensional manipulation of multiple
particles. In this work, we analyze counter-propagating shaped-beam traps that depart from this conventional geometry.
We show that projecting shaped beams with separation distances previously considered axially unstable can, in fact,
enhance the trap by improving axial and transverse trapping stiffness. We also show interesting results of trapping and
micromanipulation experiments that combine optical forces with fluidic forces. These results hint about the rich potential
of using patterned counter-propagating beams for optical trapping and manipulation, which still remains to be fully